At present, various technologies for identifying a type and operating status of an electric device are known. For example, Patent Literature 1 discloses art for identifying the type and operating status of an electric device to which power is supplied by a feeder line, by monitoring electric current flowing through the feeder line.
A high-frequency signal generating device disclosed in Patent Literature 1 causes a characteristic high-frequency electric current to be generated in the feeder line in accordance with operation of the electric device for which the operating status is to be estimated. Specifically, this high-frequency signal generating device causes a high-frequency electric current to be generated in the feeder line in accordance with operating status, by blocking for a fixed time and at fixed time intervals the electric current supplied to a specific electric device from the feeder line, when the electric device is operating.